Potassium polyphosphite composition for agricultural use and associated methods

ABSTRACT

A bactericidal and fungicidal composition having fertilizer properties, the composition containing a high percentage of potassium polyphosphite is disclosed. The composition is useful as a fungicide, bactericide, and as a fertilizer for application to plants and, particularly, commercial crops. A method of making the polyphosphite composition is described, as well as methods of using same.

RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 11/349,064,now U.S. Pat. No. 7,887,616, which was filed on Feb. 6, 2006, and whichclaimed priority from U.S. provisional application Ser. No. 60/650,378,filed on Feb. 4, 2005, the contents of which are incorporated byreference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to the field of agricultural chemicalsand, more particularly, to a chemical composition having a high contentof potassium polyphosphite and useful as an agricultural pesticidehaving some fertilizer properties.

BACKGROUND OF THE INVENTION

Phosphorus-based fertilizers are one of three critical nutrients foragriculture around the world. The others are nitrogen and potassium. Allimportant phosphorus-based fertilizers comprise phosphate, e.g.phosphate ion (PO₄ ⁻³), and occasionally some proportion ofpolyphosphates, i.e. P₂O₇ ⁻⁴, are included in the composition.Polyphosphates are ionic species formed by condensed phosphate ions (PO₄⁻³) as illustrated in formula 1.

Polyphosphates are sometimes referred to as pyrophosphates. Additionalphosphate ions may react further with the polyphosphate, P₂O₇ ⁻⁴, toform longer polyphosphates and, in general, there is a mixture ofvarying polymer chain lengths in any given sample. The presence of someproportion of polyphosphates in a fertilizer is useful for purposes ofsequestration of impurities, as suspensions aids, and for makingphosphorus more available to plants.

U.S. Pat. No. 3,917,475 describes a process for the preparation of afertilizer containing a significant amount of polyphosphate. Formationof polyphosphate is favored by high concentrations of reactants and byhigh reaction temperatures, followed by rapid cooling. However, at hightemperatures, the chemical bonds in polyphosphate can hydrolyze to yieldthe starting phosphate ion, (PO₄ ⁻³) and acid, as shown in formula 2(taken from Western Fertilizer Handbook, Interstate Publishers, Inc.,Danville, Ill., Eighth ed., p 148, 1985).

On the other hand, the lower valent phosphite, (PO₃ ⁻³), has neverplayed an important role in the commercial fertilizer industry.

A few academic research papers have been published describing alkalimetal and organic esters of polyphosphites. For instance, Payne andSkledar of the University of Glaskow in J. Inorg. Nucl. Chem., 1964,Vol. 26, pp 2103-2111 describe the preparation of “pyrophosphates” bythermal decomposition of alkali metal phosphites. An academic paper fromRussia in 1970 (CA 76:71456) describes a method of preparing ammoniumpolyphosphite by starting with phosphorous acid that has already beenpolymerized and reacting it with ammonia under pressure and at hightemperature. Using polyphosphorous acid as a reactant to producepolyphosphites, however, is not economically feasible for commercialproduction.

The analysis of polyphosphite content in a composition is difficultbecause all common wet chemical methods for determination of phosphitedepend upon reagents that first convert phosphite to phosphate. Thesereagents will break up any polyphosphite molecules present in thecomposition into individual phosphite ions. Polyphosphite, therefore,cannot be detected or quantified by the routine wet chemical methods.For instance, iodine solutions are used to oxidize inorganic phosphitesfor subsequent analysis as phosphate. Iodine will breakup any phosphitepolymer present and the polyphosphite will not be detected. Similarly,commercial labs which analyze fertilizers do not report phosphite levelsbut rather report them as phosphate. Also, during analytical proceduresrequiring heat, phosphites would typically be slowly converted tophosphate unless precautions are taken to prevent oxidation by excludingair. Furthermore, at elevated temperatures polyphosphites can beexpected to hydrolyze to ordinary phosphite ion, analogously to thehydrolysis of polyphosphates under similar conditions. Accordingly,physical methods such as nuclear magnetic resonance (NMR), high pressureliquid chromatography (HPLC), liquid chromatography, mass spectrometry(MS), and other physical molecular weight determining methods are usefulmethods for characterizing polyphosphites.

NMR provides a unique method of detecting phosphite because in mostcases, and particularly when in solution, it exists with a hydrogenattached to the phosphorus atom (HPO₃ ⁻²). Sophisticated NMRinstruments, such as the Varian VXR-300S spectrometer, can not onlydetect and measure P³¹ but can also simultaneously perform measurementson atoms such as hydrogen attached to phosphorus or carbon by transferpolarization. Such an instrument can, therefore, detect and measurephosphite in the presence of other phosphorus species without ambiguity.

Inorganic phosphite compositions such as potassium phosphite are knownto be useful as fungicides, as described in U.S. Pat. Nos. 5,736,164,5,800,837, and U.S. 2003/0029211A1, for instance. As is common with allcommercial chemicals, however, and particularly so with environmentallysensitive chemicals such as fungicides, less is often better. Therefore,there is always a need for enhanced performance at an equivalent dose.

In this context, potassium phosphite would be particularly usefulbecause it would provide the second important nutrient of the threecritical plant nutrients, potassium. Moreover, a polyphosphite can beexpected to provide the sequestration and slow release advantages knownwith polyphosphate, although phosphites are more active fungicides.

Currently available commercial methods for preparation of fertilizergrade potassium phosphite, KH₂PO₃ and/or K₂HPO₃, are carried out bycharging an aqueous potassium hydroxide solution to a mixing tankequipped with an agitator and with cooling means (commonly called abatch reactor). Alternatively, potassium carbonate could be used as areactant instead of potassium hydroxide. Phosphorous acid is added tothe potassium hydroxide, slowly at first, then more rapidly toward theend of the reaction. This process is subject to a number of problems.

The reaction can be violent and on a large scale, even with goodagitation and cooling, the reaction can run away explosively. In fact,at least two fatalities and numerous injuries have resulted recentlyfrom such run away reactions. During the early addition of phosphorousacid, even if the reaction does not run away, localized excessive heatrelease occurs, even when the over all temperature is at or below 200°F. Furthermore, it is known in the art that hazardous toxic phosphinegas, which has a characteristic garlic-like odor, may be emitted duringthe reaction when the temperature reaches 150° F., which creates ahazard unless properly absorbed. In addition, a batch reactor isdifficult to seal and prevent oxygen in the air from entering, whichreadily oxidizes the phosphorous acid to phosphoric acid, preventingformation of phosphites.

The necessary slow addition of the acid results in the hydroxide alwaysbeing in excess until close to the end of the reaction, thus hinderingformation of the desired polyphosphite. As a consequence, and also dueto low temperatures, previous processes can be expected to providelittle or no formation of polyphosphites.

Yet another potential problem which occurs in batch processes is poorcontrol of the addition rate of and total quantity of reactants presentin the mixture. Extra care must be taken in measuring ingredients and inthe rate of addition which is time consuming and labor intensive. Lackof attention by the technician can lead to an explosive run awayreaction.

U.S. Pat. No. 3,585,020 by Legal, Jr., et al. describes a process forforming a free-flowing, granular, non-burning and non-crumbling 7-40-6fertilizer composition. Reference is made at column 3 to the use of aninline mixer. However, the use of spargers in the process suggests thatit is specific to batch processing. In any case, the reference by Legal,Jr., et al. is specific to forming granular materials quite differentfrom the liquid solutions prepared in the present invention.

In U.S. Pat. No. 3,957,947 Yamada et al. describe a process for thecontinuous production of aqueous basic aluminum salt solutions. Theproducts of Yamada appear to be deodorants, and while a short tubularreactor is involved, it is necessary to provide heat on an indirectbasis and the overall reaction scheme is quite different from that ofthe present invention.

The Environmental Protection Agency, classifies potassium phosphitecompositions as “biopesticides” under their regulatory classification,for reduced registration requirements. As such, the active ingredient,mono- and di-potassium salts of phosphorous acid are synthesized activeingredients involving a mixed mode of action by direct toxicity to plantpathogens, and by activating the plants natural defense mechanisms, indisease suppression or elimination.

Potassium phosphites are systemically absorbed by the plant and aremobile within the plant, translocating to the new growth via both thephloem and the xylem. They are rapidly absorbed by the leaf tissue androots for maximum and efficient plant use by moving systemically upwardand downward in the plants vascular system, including the root system.The mode of action is thought to be two-fold, first acting within thefungus by “walling off” the pathogen, killing off surrounding cells whenattacked by disease or insects, and inhibiting further fungus growth.This is observed as yellowing around a diseased area. Secondly, theplant then responds further by activating the plant's own immuneself-defense system, through rapid cytological action, and triggeringother cellular phytoalexin accumulations and metabolic changes and otherresistance inducers. Various chemical compounds are released that alertthe rest of the plant to begin producing other compounds that increaseplant resistance to infection or attack at other sites on the plant.These two types of responses are known as systemic acquired resistance(SAR) and induced resistance (IR).

As a result, phosphites are highly selective, non-toxic fungicidesactive against numerous fungal pathogens, and provide both protectiveand curative responses against such plant disease isolates ofPhytophthora, Rhizoctonia, Pythium, and Fusarium, and other plantdiseases—but typically not against bacterial diseases.

The extreme difficulty, or even the total lack of bacterial diseasecontrol, by induced systemic resistance compounds, including those basedon the salts of phosphorous acid, and particularly the potassium salts,is well known. For example, the benchmark product, “Aliette”, a productcomprising aluminum salts of phosphorous acid and EPA-registeredpesticide, does not provide for any bacterial disease control.

Accordingly, the skilled will appreciate that a need exists for aneconomical and safer commercial process for the preparation of apotassium polyphosphite composition having enhanced effectiveness as anagricultural fungicide.

SUMMARY OF THE INVENTION

With the foregoing in mind, the present invention advantageouslyprovides a fungicidal composition having fertilizer properties andcontaining at least 50% by weight of potassium polyphosphites in aqueoussolution. In a preferred embodiment of the invention, the compositionconsists essentially of potassium polyphosphites in aqueous solution.The present composition may also contain potassium phosphite and atleast 25-75% by weight or more of potassium polyphosphite.

Additionally, described is a method of making a fungicidal compositionhaving fertilizer properties and containing at least about 25-75% byweight of potassium polyphosphite. The method comprises reactingphosphorous acid and potassium hydroxide in aqueous solution at atemperature of at least approximately 270° F. and rapidly cooling theaqueous solution to a temperature below approximately 90° F. A morepreferred method includes making a composition consisting essentially ofpotassium polyphosphite by reacting phosphorous acid and potassiumhydroxide in aqueous solution at a temperature above 270° F. and rapidlycooling the aqueous solution to a temperature below approximately 90° F.The method may be carried out wherein reacting is conducted at betweenabout 300°-350° F. and wherein cooling is conducted at about 90° F. orless.

The polyphosphite composition has fertilizer utility and a method offertilizing a plant includes applying an effective amount of thecomposition. The present invention also includes a method of treating aplant for a fungal infection, the method comprising applying aneffective amount of one of the polyphosphate compositions disclosed. Thecomposition of the present invention may also be used for treating aplant for a microbial infection, that is, of an etiology other than afungus, the method comprising applying an effective amount of thecomposition.

Moreover, the present polyphosphite composition has demonstratedeffectiveness against bacterial diseases, including the bacterial plantpathogen, Xanthomonas axonopodis pv. citri (Xac), which is the cause ofAsiatic citrus canker, where no other cure is currently available.

In addition, Ralstonia solanacearum, a bacterial wilt infection, isvirtually 100% controlled with the present polyphosphite composition. Ithas been discovered that a unique third mode of protection, is at work,in that control of the organism is by a previously unrecognizedbacteriostatic method, rendering the pathogen unable to reproduceitself.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the features, advantages, and benefits of the present inventionhaving been stated, others will become apparent as the descriptionproceeds when taken in conjunction with the accompanying drawings,presented for solely for exemplary purposes and not with intent to limitthe invention thereto, and in which:

FIG. 1 is a cross-sectional side elevation of an apparatus which may beused in preparing the composition according to an embodiment of thepresent invention;

FIG. 2 is a graph showing activity of the present polyphosphitecomposition against some bacterial agents of plant disease;

FIG. 3 NMR spectra for sample PFS 026, as described in example 7;

FIG. 4 NMR spectra for sample PFS 030, as described in example 7;

FIG. 5 NMR spectrum for P³¹ for sample PFS 002, as described in Example5; and

FIG. 6 is an NMR H¹ polarization transfer spectrum also for sample PFS002.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. Unless otherwise defined, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionpertains. Although methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of the presentinvention, suitable methods and materials are described below. Anypublications, patent applications, patents, or other referencesmentioned herein are incorporated by reference in their entirety. Incase of conflict, the present specification, including any definitions,will control. In addition, the materials, methods and examples given areillustrative in nature only and not intended to be limiting.Accordingly, this invention may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments set forth herein. Rather, these illustrated embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Other features and advantages of the invention will be apparent from thefollowing detailed description, and from the claims.

Apparatus for Use in the Present Invention

A preferred embodiment of the present invention employs the cross-pipereactor described in U.S. Pat. No. 4,724,132 (the '132 patent) incombination with a down-stream mixer which is a static in-line mixer,the static in-line mixer can be extremely short or, in fact, the staticinline mixer could comprise the entire length of the pipe 60 as shown,in which case the static in-line mixer would essentially deliver productinto receiving tank 70 and FIG. 1 would be modified to basically deletepipe 60. The primary criterion which would set the length of the staticin-line mixer, if it is used, is to insure that reaction issubstantially complete prior to the time the product enters thereceiving tank 70 as shown in FIG. 1. Generally speaking, if the staticin-line mixer (or some other mixer) is not used downstream thecross-pipe reactor the length of the pipe 60 should be increased toinsure substantially complete reaction with a decrease in the length ofpipe 60 if a static in-line mixer is used. The exact length of thestatic in-line mixer and/or the pipe 60 can easily be determined bystandard chemical engineering practices.

The excellent mixing, polymerization and temperature obtained with thecross-pipe reactor creates a greater potassium hydroxidesolution/acidulation surface area, and insures good conversion of thepotassium compound(s) to polyphosphite salt. Acidulation is, of course,the process of adding acid, and generally the amount of mineral acid,phosphorous acid, is specified with respect to the amount of potassiumhydroxide. This can easily be established by one skilled in the art.

As indicated, even more pronounced effects are obtained with theaddition of a static in-line mixer down-stream from the cross-pipereactor. A typical static in-line mixer useful in the present inventionand, in fact, the one that has been used to date, is disclosed in U.S.Pat. No. 4,093,188 Horner, hereby incorporated by reference. Theparticular static in-line mixer disclosed has stationary bafflesproviding sinuous, non-parallel spiraling flow paths to promote thoroughand homogeneous intermixing of fluids. It is not mandatory to use thatprecise static in-line mixer and other static in-line mixers, also knownas stationary baffle mixers or interfacial surface generators, can beused. For example, it is believed that stationary baffle mixers orinterfacial surface generators as disclosed in U.S. Pat. Nos. 3,190,618;3,620,506; 3,643,927; 3,652,061; 3,923,288; 3,947,939 and Reissue No.28,072 could be used with equal success, and all of these patents arealso incorporated by reference. Other mixers could likely be usedinstead of a static in-line mixer, for example, as can be appropriatelyselected by one skilled in the art from the Chemical Engineers'Handbook, John H. Perry, Editor, Third Edition, McGraw-Hill Book Co.,Inc., pp. 1195-1231.

After the reactants have passed through the cross-pipe reactor 10, themixer 50 and pipe 60, the reacted mixture is conveniently dischargedinto a receiving tank 70. Generally, it is preferable to substantiallycomplete reaction prior to introduction of the product into thereceiving tank 70. As one skilled in reaction kinetics will appreciate,there will be some slight amount of reaction in the receiving tank 70,but this is not of consequence if any reasonable amount of care isexercised over process control, as would be understood by a chemicalengineer. The discharge is usually above the level of the liquid in thereceiving tank 70 in order to achieve faster flash cooling. If thedischarge is below the liquid level, reducing to some degree the coolingcapacity, the conversion ratio from metal hydroxide solution to salt isslightly improved. As will be appreciated by one skilled in the art, theuse of a receiving tank is merely a convenient means to use a cool,large mass of product to inexpensively cool the product received frompipe 60. The composition should be cooled to approximately 90° F., orless, as rapidly as possible. Any conventional means could be used toachieve this cooling effect.

The determination and adjustment of optimum reaction parameters will bewell within the skill of the chemical engineer. The product can berecirculated from receiving tank 70 through cooling means (not shown)via pump 90. If desired, some product can be sent to storage via line100 but normally the greater volume is recirculated over a packed column110 through which air is blown by fan 120 in order to cool the productprior to storage. Also, as one skilled in the art will appreciate,pumping means are provided throughout the system as needed; these areconventional and are not shown. Further, the skilled will recognizethat, since a mineral acid is being used, conventional process equipmentresistant to acidic conditions will be used, typically stainless steel.

Description of the Process

Evidence of the makeup of the composition is found in NMR results ofseveral samples and from chemical tests. Samples were prepared by theuse of the apparatus of the present invention as shown in FIG. 1 anddescribed below. NMR analysis was conducted by Process NMR Associates,LLC, using a Varian VXR-300S Spectrometer. Spectra were recorded and theposition of the peaks noted in terms of parts per million of fieldstrength (ppm) relative to the standard inorganic phosphate peak.Simultaneously, the samples were examined for the hydrogen atom attachedto the phosphorus atom using the transfer polarization technique.Concentration, different counter-ions, such as ammonium, sodium, orpotassium can cause a small change in position of the peaks, thereforethe exact position of the peaks in a given spectrum is not definitive.However, the relative position of one peak to another, such as phosphateversus phosphite, is useful. Potassium phosphite alone exhibits a singlesharp peak for the P³¹ atom and a correspondingly sharp peak in thetransfer polarization spectrum for the H¹ atom that is attached to the Patom of all inorganic phosphites. To the contrary, no correspondingtransfer polarization spectrum for H¹ is found for polyphosphites, whichclearly indicates that there are no longer H¹ atoms attached to thephosphorus and that the starting material, HPO₃ ⁻², has been chemicallychanged. In addition, in confirmation of polymeric character, the peakis no longer sharp (half width of about 10 to 20 Hz) but very broad(half width of about 30 to 100 Hz). The breadth of such P³¹ NMR peaks,at a given field strength, is the result of the different positions ofphosphorus atoms in the polymer and the different molecular weights ofoligomers. Accordingly, each atom yields a signal indicating its uniqueenvironment and, since the signals are only slightly different, theresult is a broader peak. In the case of phosphite and polyphosphite,the peak positions are very near each other and a broad peak can cover asmaller narrower peak. Under the different conditions in the variousexamples of the present invention, the composition prepared may containmore or less potassium polyphosphite with the balance being simplepotassium phosphite. However, several samples have been prepared by thisinvention that give no detectable response for P³¹-H¹ in transferpolarization NMR analyses, thereby indicating that the samples arenearly 100% polymerized PO₃ ⁻³, polyphosphite. Furthermore and analogousto polyphosphate chemistry, it has been found that the compositionprepared by the present invention readily generates free acid when theyare heated above ambient temperature thereby providing furtherconfirmation of the proposed structure, as illustrated in FIG. 2. Theamount of free acid continues to increase with time as the compositionis held at an elevated temperature.

A most preferred embodiment in a continuous process of the presentinvention will be described with reference to the FIG. 1 and comprises ametal hydroxide solution, e.g., potassium hydroxide solution, as anaqueous solution reacted with a mineral acid, e.g., phosphorous acid,with water being added as necessary to adjust specific gravity. Themetal hydroxide solution is pumped into port 20 of the cross-pipe tee10, the mineral acid is pumped to port 30 and the water is pumped intoport 40. Reaction begins on contact of the metal hydroxide solution andmineral acid and the mixture of the reactants is forced substantiallyimmediately into the static in-line mixer 50 where reaction continues tooccur. The rate of total feed is controlled so that the temperature astaken about midway up the pipe 60 above the in-line mixer 50 ismaintained at a desired level, and preferably at about 300° F.+/−0.50°.Generally speaking, the reaction continues in the pipe 60. Since thereaction of the present invention is exothermic, external heat need notbe supplied to the system. As a general practice, I simply measure thetemperature about one-half way up the distance of the pipe 60 as shownin the FIG. 1 by temperature indicator 130. However, the temperaturecould easily be measured anywhere between the cross-pipe reactor anddischarge into the receiving tank 70 as shown in FIG. 1. The ratio ofthe potassium hydroxide solution to phosphorous acid fed is adjusted tomaintain product pH specification at the desired level, depending on thetype of product being manufactured. The rate of water addition iscontrolled to maintain the desired product specific gravity. Productspecific gravity is a relatively precise number and is typically set bythe tolerances of fertilizer control laws. It can be freely selected byone skilled in the art. Various examples follow, including one exampleof a prior art batch process which is inadequate for use in the presentinvention.

EXAMPLE 1

This example is a batch process and represents prior art methods, ratherthan a method of the present invention. It is presented here to show howthe prior art is unable to achieve the results provided by the presentinvention.

Into a 5,000 ml stainless steel laboratory blend tank outfitted with anelectric driven propeller-type mixer, a 2,000 gram batch of a 70%solution of phosphorous acid was dissolved and prepared from 1,414 gramsof 99% white, crystalline phosphorous acid, into 586 grams of distilledwater. A 70% solution of phosphorous acid is the normal concentrationcommercially available that is typically used in the production ofphosphorous acid products. Heat was applied in order to keep thetemperature at 70° F. throughout the process and the mixture was stirredvigorously for approximately 10 minutes to obtain a uniform, clearsolution of phosphorous acid. This solution was then poured off into aflask and stoppered. Of this solution, 918 grams was weighed intoanother flask and stoppered. 1,239 grams of 50% KOH was weighed andstored in a separate flask, both weighed products being of sufficientquantity in order to blend a 2,000 gram batch of a typical potassiumphosphite product by the batch method, as known by those practicing inthe art. There was a negative −157 gram imbalance of water which wasexpected to evaporate off as a result of the exothermic reaction. The1,239 grams of KOH was poured into the above described 5,000 ml tank,and agitation begun. At this point the laboratory ventilation systemshould be engaged and the technician should wear proper laboratorysafety attire, including goggles, for handling hazardous materials.Then, the addition of the 918 grams of acid was started with continuousagitation. The rate of addition of acid was maintained as fast aspossible but without causing vigorous boiling of the water. Duringaddition of the first 200 grams of acid, the batch began to boilvigorously, with the temperature reaching about 150° F. Upon coolingsufficiently, another 200 grams of acid was added slowly to the boilingpoint again continuously from the mixture. When most of the calculatedamount of acid had been added, a very faint garlic-like odor wasdetectable, indicative of the formation of phosphine. The lab wasimmediately vacated until it was determined that the mixture had stoppedboiling and that the lab had been properly ventilated. Personnelreentering the lab donned protective masks. It was not possible tocomplete the batch without exceeding about 130° F., without the materialboiling over and out of the tank, and without the further risk ofproducing phosphine gas. The final pH was adjusted to 6.8 and themixture was cooled in a water bath.

EXAMPLE 2

This example describes the general process employed in the invention, inthe temperature range as used also in examples 4 and 6. A run wascarried out using equipment as shown in the above describe crosspipereactor and FIGURE including a special mixing device, i.e., an opencross-pipe reactor with a static in-line mixer, as disclosed in U.S.Pat. No. 4,093,188 Horner. It is commercially available under the tradename STATA-TUBE and is a motionless mixture manufactured by TAHIndustries, P.O. Box 178, Imlaystown, N.J. 08526, (2″ L.D. times.96″length). In the Examples herein the runs were on a commercial scaleusing a cross tee reactor where the ports had an inner diameter of about2 inches″ and the pipe was about 96″ in length having an inner diameterthe same as the cross tee reactor ports. Obviously these dimensions arenot restrictive and smaller and/or larger devices can be used. Allprocess lines were stainless steel. Reactants were pumped into thecross-pipe injection ports as follows: a 50% solution of potassiumhydroxide at a rate of approximately 21 gallons per minute (port 20),and 70% phosphorous acid at a rate of 15 gallons per minute (port 30).Water at a rate of approximately 3 gallons per minute was injecteddirectly into the receiving tank, in order to attain the highest pipetemperature possible. The reaction product was simply flowed into areceiving tank above the liquid level for ease of operation. During therun frequent samples were taken from the tank for pH and specificgravity checks, and acid and water flows were adjusted to maintain thesevalues at the desired levels, i.e., pH 6.8, specific gravity 1.45 (thesevalues are the same in the following Examples unless indicated to thecontrary). Acidulation and conversion were thus controlled. During therun the temperature at the midpoint of the pipe fluctuated from 260° F.to 275° F. The reactionary product entering the receiving tank wasinstantly cooled to about 115° F. and was pumped to a finished productstorage tank at a rate of approximately 33 gallons per minute. As aresult of the evaporative cooling process taking place, voluminous steamplume was continuously emitted, and sampled for any trace of a garliclike odor, and none was detected.

EXAMPLE 3

Using the process of Example 2, the reactants were introduced at lowerrates, sufficient to keep the temperature at the midpoint of the pipebelow 200° F. and a small portion of the resulting composition wasimmediately brought into the laboratory and packaged for rapid shipmentto NMR Associates, LLC in Connecticut for testing by NMR. The NMRanalysis revealed strong narrow peaks both for P³¹ and H¹, which isindicative of the presence of the inorganic salt potassium phosphite.

EXAMPLE 4

A run was carried out using the process of Example 2 where thetemperature at the midpoint of the pipe was between 260° F. and 275° F.and a small portion was immediately brought into the laboratory andpackaged for rapid shipment to NMR Associates, LLC in Connecticut forNMR analyses. The NMR analysis revealed a single broad strong peak forP³¹ and only small evidence of H¹ attached to P³¹ under the polarizationtransfer test, which indicates that most of the inorganic potassiumphosphite had been converted to polyphosphites but that somemonophosphite remained.

EXAMPLE 5

The process of Example 2 was followed, where the temperature at themidpoint of the pipe was maintained between about 270° F. and 285° F. Asmall portion was immediately brought into the laboratory and packagedfor rapid shipment to NMR Associates, LLC in Connecticut for NMRanalyses; this was labeled sample PFS 002. As shown in FIGS. 5-6, theNMR analysis revealed a single broad strong peak for P³¹ but no evidenceof H¹ attached to P³¹ under the polarization transfer. This resultindicates that essentially all of the inorganic potassium phosphite hadbeen converted to polyphosphites.

EXAMPLE 6

The process of Example 2 was carried out, but where the temperature atthe midpoint of the pipe was maintained between about 260° F. and 275°F. Eight days later, a five-gallon sample was taken from the storagetank and portions were subjected to heat treatment at varioustemperatures as follows. The sample had a specific gravity of 1.46, a pHof 6.5, and the dry solids content was about 53%. The NMR showed a largenarrow peak for P³¹ and also a significant peak for H¹ under transferpolarization. A portion, 232 g, was heated over a period of 13 minutesin an open stainless steel pan until it boiled at 116° C. Weightmeasurements showed a loss of 53 g of water. Further heating for aperiod of 15 minutes resulted in an additional loss of water of 33 g andthe boiling point climbed to 145° C. The pH was 3. Another portion of223 g of the original sample was heated in a similar manner but for lesstime so that the solution remained homogeneous. The pH was 4.

These experiments showed that free acid was being liberated uponheating, which is to be expected when hydrolysis of polyphosphiteoccurs. These data are consistent, indicating a sample containing amixture of potassium phosphite (monomer) and polyphosphites.

EXAMPLE 7

A mixture of phosphoric acid and phosphorous acid was prepared for usein the reactor of the present invention. Five hundred pounds (500 lb) ofsolid 99% phosphorous acid was dissolved in 1500 lb of 75% phosphoricacid in order to increase the concentration of reactants by reducing theamount of water, and so as to subsequently increase the reactiontemperature. This acid mixture was reacted with a 50% solution ofpotassium hydroxide, the reaction expected to yield a mixture ofpotassium phosphate and potassium phosphite. The test run lastedapproximately 3 hours.

The conditions of the reaction were varied over this period of time inorder to study the effect of operational parameters. Five differentconditions were studied. A small sample (7A) was withdrawn after eachchange in the reaction conditions after the system had stabilized.Sample number PFS026 was obtained when the reaction temperature wasabout 265° F., the pH was 8.22, the specific gravity was 1.475, and thesample temperature was 105° F. The NMR spectra for this sample are shownin FIG. 3. The P³¹ spectrum shows two sharp peaks indicative ofpotassium phosphate and potassium phosphite. The H¹ spectrum for thehydrogen attached to the phosphorus atom, obtained by polarizationtransfer, confirms the presence potassium phosphite as expected.

Sample PFS030 (7B) was obtained when the reaction temperature was about300° F., the pH was 7.6, the specific gravity was 1.44, and the sampletemperature was 100° F. The NMR spectra are shown in FIG. 4.Surprisingly, the P³¹ spectrum shows a very broad peak consistent withformation of polymer. The spectrum also shows small peaks at the top ofthe broad peak indicative of small amounts of unreacted potassiumphosphate and potassium phosphite. Also surprisingly, the H¹polarization transfer spectrum shows an absence of hydrogen atomsattached to the phosphorus atom and which clearly indicates that anunexpected chemical reaction has resulted in almost complete polymerformation.

The results obtained in the examples set out above are also shown inTable 1, below, for easy comparison.

TABLE 1 SAMPLE TEMP. IN ° F. PHOSPHINE MONO PO₃ POLY PO₃ EX. 1 (batch)≦150° YES N/A N/A EX. 2 260-275° NO N/A N/A EX. 3 <200° NO YES NO EX. 4260-275° NO YES YES EX. 5 270-285° NO NO YES EX. 6 260-275° NO YES YESEX. 7A ~265° NO YES YES EX. 7B ~300° NO NO YES

Accordingly, in the drawings and specification, there have beendisclosed typical preferred embodiments of the invention, and althoughspecific terms are employed, the terms are used in a descriptive senseonly and not for purposes of limitation. The invention has beendescribed in considerable detail with specific reference to theseillustrated embodiments. It will be apparent, however, that variousmodifications and changes can be made within the spirit and scope of theinvention as described in the foregoing specification and as defined inthe appended claims.

1. A method of making a fungicidal composition having fertilizerproperties, said composition containing about 25-75% by weight ofpotassium polyphosphite, the method comprising: reacting phosphorousacid and potassium hydroxide in aqueous solution at a temperature of atleast approximately 270° F.; and rapidly cooling the aqueous solution toa temperature of approximately 90° F. or less.
 2. The method of claim 1,wherein reacting is conducted at between about 300°-350° F.
 3. A methodof making a fungicidal composition having fertilizer properties, saidcomposition consisting essentially of potassium polyphosphite, themethod comprising: reacting phosphorous acid and potassium hydroxide inaqueous solution at a temperature above 270° F.; and rapidly cooling theaqueous solution to a temperature at or below approximately 90° F. 4.The method of claim 3, wherein reacting is conducted at between about300°-350° F.